This invention relates to the cleaning of disks containing encoded information, such as phonorecords and videodiscs, and more particularly to electrostatically cleaning such disks with an electrostatically activatable flexible strip.
Dust particles (i.e., foreign matter) on the surface of a phonorecord can interfere with the fidelity with which the sound, i.e., the information encoded on the phonorecord, is reproduced when the phonorecord is played. The annoying and disruptive transients, popping and crackling resulting from the dust particles are well known. Substantially the same problem occurs with dust particles on videodiscs, namely the pictures and the sound may be distorted during playback because of the presence of dust particles.
Various systems to deal with the problems of cleaning dust particles off phonorecords have been proposed. Among them are those systems shown in the following U.S. Pat. Nos.: 2,958,529 to King; 2,977,127 to Mertes; 3,150,401 to Taylor et al.; 3,185,485 to Brubaker; 3,618,958 to Schmidlin; 3,822,065 to Arbib; 3,958,292 to Powell; 3,965,520 to Maier; and 3,992,018 to Plummer et al.
The patent to King discloses an attachment A for a phonograph pick-up arm for removing grit and dust from the grooves of phonorecords as well as for eliminating static electricity created by the needle rubbing along the record. The attachment includes a plastic or foam rubber sponge 36 disposed adjacent the phonograph needle, labelled 16, which purportedly (see col. 3, 11. 12-20) eliminates static electricity imparted by the moving needle to the dirt on the record. Sponge 36 rests on the record which it is cleaning and takes the shape of the grooves and ridges of the record at its lower surface to clean the entire surface, presumably mechanically.
The patent to Mertes shows a device for cleaning phonorecords having two arms 1 and 2 covered with a pad 6 of resilient synthetic resin foam (preferably polyurethane foam). According to the patent, the foam pad "wipes out" electrostatic charges on the phonorecord being cleaned. Preferably (see col. 1, 11. 62-66) pad 6 is impregnated with a liquid to increase the cleaning effect. Although the device of this patent is intended to be used as shown in FIG. 2, it can also be opened completely so that arm 1 lies substantially in the extension of arm 2 and arm 2 can then be placed over the spindle of the turntable to span the record.
The Taylor et al. patent describes a phonorecord cleaner 10 having a pair of brushes 36 for physically dislodging dust from the surface of the record. Cleaner 10 also includes opposed strips 66 of polonium impregnated material for radioactively neutralizing static electricity on the record to be cleaned. The Brubaker patent discloses a tone arm mounted dust remover for phonorecords having nylon brush assembly bristles 33 for physically ejecting dust from the grooves of the record to be cleaned and a fluid moistened plush pad 37 for collecting the dust ejected by bristles 33 and for removing any electrostatic charge from the record. The Schmidlin patent shows a tone arm attachment for a phonorecord which includes a felt mat for wiping dust from the phonorecord during play without scratching the surface of the record.
The patent to Arbib is very similar to the Brubaker patent in that both disclose tone arm mounted attachments with a brush and a plush pad. In the Arbib patent either the brush (14) or the pad (23) can be moistened with water or a special anti-static or cleaning fluid if desired.
The Powell patent describes a roller covered with adhesive tape for cleaning phonorecords, the bond strength between the adhesive particles exceeding that between the adhesive particles and the record face so that adhesive particles do not separate from the tape and become attached to the record. To clean a record, the roller with fresh adhesive tape exposed is rolled across the surface to be cleaned before the phonorecord is played. The patent to Maier shows a similar, non-real time (i.e., not during playback) cleaning system except that in the case of the Maier patent the cleaning device is not an adhesive coated roller but rather is a special brush dampened with an anti-microbial liquid cleaning composition.
The Plummer et al. patent describes a cleaning system for phonorecords having a plush cleaning element 6 mounted on a lid 11 of the phonorecord player. When the lid is closed element 6 rests on the phonorecord along the dotted line 5. Alternatively (see col. 2, 11. 26-39) the cleaning element can be mounted on a cantilevered arm extending across the phonorecord, the arm being counterbalanced to enable the cleaning element to rest on the record with the proper pressure.
Applicant is also aware of another phonorecord cleaning apparatus sold by Musonic Ltd. of St. Albans, England under the trade designation Colton Electroduster. This apparatus includes an arm, supported by a pillar at the edge of the turntable, which terminates in a rubber rimmed wheel resting upon the label of a phonorecord to be cleaned. According to a review article on the apparatus, the wheel rotates as the record is played to cause an electrostatic belt of soft fibers to traverse the record surface radially. According to the article, the belt is charged during play of the record by passage over a cleaning pad, which pad also collects any loose debris attracted by the belt. Simultaneously, a velvet tracking pad laterally traverses the disk before the stylus to clean the grooves of the phonorecord while the record is being played.
Also of interest to this application are devices such as that shown in U.S. Pat. No. 2,149,556 to Smith for electrostatically cleaning furniture and other fabrics.
The devices and systems mentioned individually suffer from several disadvantages, among them being undue complexity, the need for or desirability of a cleaning or antistatic fluid, interference with the playback of the phonorecord caused by mechanical contact between a portion of the system and the surface of the record during playback, an inability to provide real-time (i.e., during playback) cleaning of the phonorecord, and expense of the systems themselves.